This application claims the priority of German Patent Application No. 197 31 283.7, filed Jul. 21, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a diagnostic tester for electronic control devices in various types of motor vehicles and, more particularly, to a diagnostic tester which can be connected by a plug connection in any motor vehicle to a diagnostic plug connection connected with the control devices to be diagnosed. The connection is standardized mechanically with a predetermined number of plug contacts but not, however, in terms of the signal assignments of the plug contacts and the electrical properties of the signals to be transmitted.
Modern motor vehicles have a permanently installed diagnostic plug connection for connecting a diagnostic tester. The connection is connected on the side of the motor vehicle with the control devices to be diagnosed. The diagnostic plug connections in the various vehicle types are identical mechanically, especially as regards the specified number of plug contacts and as regards the shape of the diagnostic plug connection, on the basis of international standards for so-called on-board diagnostic systems for motor vehicles.
Many motor vehicle manufacturers currently make conventional use of the 16-pole PBD II plug according to SAE standard SAE-J-1962 as the diagnostic plug connection. This diagnostic plug connection is partially not standardized in terms of the way that the signal is applied to the plug contacts and in terms of the electrical properties of the signals to be transmitted. For example, electrical fault diagnosis signals can be applied through the conventional diagnostic bus leads in various vehicle types to different plug contacts of the diagnostic plug connection. In addition, the electrical properties of the signals to be transmitted, especially as a result of internal resistances, input switching thresholds, or output levels that differ in the vehicle, vary from vehicle to vehicle. This problem has been solved in the past by supplying a plurality of different kinds of adapter cables as plug connections between the motor vehicle and the diagnostic device for use with the diagnostic tester. The cables create the necessary electrical connections and adjustments in each case to the electrical properties for the various vehicle types. This solution is especially disadvantageous with respect to cost, logistics, and the probability of incorrect operation by confusing the adapter cables.
Hence, the goal of the present invention is to improve upon the diagnostic testers of the above-mentioned type such that the above disadvantages are eliminated.
This goal is achieved by a diagnostic tester for electronic control devices which can be connected by a plug connection in any motor vehicle to a diagnostic plug connection connected with the control devices to be diagnosed. The connection is standardized mechanically with a predetermined number of plug contacts but not, however, in terms of the signal assignments of the plug contacts and the electrical properties of the signals to be transmitted The plug connection is a universal plug connection that is identical for the various types of motor vehicles. The connection is mechanically adapted to the standardized diagnostic plug connection. An adapter unit is connected at the diagnostic tester side of the universal plug connection. The adapter unit automatically creates the necessary electrical connections between the plug contacts of the universal plug connection and the central processing unit CPU of the diagnostic device in accordance with the signal assignments of the plug contacts made for each type of motor vehicle. Advantageous improvements of the invention are also described herein.
The plurality of adapter cables is replaced in the diagnostic tester according to the present invention by a single universal plug connection for all types of motor vehicles. The function of the plurality of adapter cables is assumed by a signal adapter unit which automatically produces the necessary electrical connections and adjustments to the electrical properties of the signals to be transmitted. Advantageously, the signal adapter unit has for this purpose a module that can be reprogrammed in terms of its function and/or its pin assignments, said module being known for example as a so-called FPGA (field programmable gate arrays) module made by the Xilinx company. Since this module is basically unsuitable for processing motor vehicle signals, especially those at a high level, this module operates with drivers in the form of universal transmitter and/or receiver units. Preferably, a driver is assigned to each plug contact of the universal plug connection. The drivers can operate, for example, as receivers, transmitters, or as transmitters and receivers for bidirectional signals.
The operation of the driver can be configured by means of the reprogrammable module. Similarly, the electrical properties of the signals to be transmitted are preferably adapted by suitable configuration of the drivers by means of the reprogrammable module. Because the module can be reprogrammed in terms of its function and assignments, for example, similar signals in its information content that are assigned to certain inputs or outputs of the diagnostic tester or of its CPU can be applied to these inputs or outputs, even if these signals are being transmitted over different plug contacts of the diagnostic plug connection :and with different electrical properties (differences in signal level for example).
Preferably, the adapter unit, as the result of the application of certain input signals, recognizes which type of vehicle is to be diagnosed at the moment and then adapts automatically to the corresponding signal assignments of the plug contacts and to the electrical properties of the signals to be transmitted. Input signals of this kind for detecting a specific type of motor vehicle can, for example, be produced manually for example by operating a switch on the diagnostic tester or by means of a signal, transmitted through a specific plug contact from the motor vehicle, that is capable of distinguishing the types of motor vehicles.
A considerable cost savings is achieved with the diagnostic tester according too the present invention since the additional adapter contributes only insignificantly to the total price of the diagnostic tester, while the plurality of adapter cables can be eliminated. Ion addition, the operation of the diagnostic tester is simplified and the possibility of improper operation is eliminated by using a single universal plug connection and a partially fully automatic adapter.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.